For live use I think the RFX is ok. I think the most useful part is the Multisetup part. It basically enables able you to record snapshorts of the Midi Mix screens - yum. It's great because you can assign FX as part of a multisetup too. You can flick between multisetups fairly quickly, the Midi Mix info changes almost instantaneously however any effect settings seem to to take a bit longer to load in. Unfortunately you can't change to different Multisetups via midi (well I haven't sussed it yet), a shame really as it would have been nice to tuck the emu away somewhere when playing live.
The effects are fine for live use but in my opinion they're not good enough to record with. There is a small amount of midi modulation available although not as much as I would have liked to have seen e.g. no realtime modulation of Karplus-Strong effects on the delays
I haven't suffered with the live 'outburst problem' yet but I think that's because when I play live I only use 2 main outputs - left and right.
It can be a steep learning curve getting to know the RFX inside out, but to be honest I love a technical challenge, I suppose it depends how quickly you need results.
The 'random panning' problem, well, where do I start. When the problem gets going it's terrible and makes recording a joke. Even more of a joke is the fact that the rfx adat option mirrors the analogue outputs so I wont be buying that option in the future. I can't believe that Sound on Sound managed to review the RFX and not catch up on this, in my opinion they just flipped through the menus and envisaged it's possibilities
(if you hand't guessed it was this review that made me buy it ).
Some tracks that I play live are so badly effected that I have to make them mono whereas others aren't that effected at all
Summary, if you can get one cheapish and want to do live things with it then go get one. In my opinion it's too much of pain for studio use.